The conventional telephone system has gained almost universal acceptance in developed countries, and widespread acceptance throughout the rest of the world. However, this technology is subject to the limitation that the two or more participants to a call must be present at respective telephones at the same time for a call to take place. Public telephones are provided for convenience of use when away from home or office telephones, but these telephones are only conveniently useful for making outgoing calls and are generally inconvenient for receiving incoming calls.
Telephone paging systems were introduced some years ago to enable a caller to send a simple message to a portable receiver which the recipient could carry around. Mobile telephony has subsequently been introduced to enable mobile callers to send and receive calls. As mobile telephone technology has achieved greater market penetration, a number of social penalties have become apparent. For instance, users are tempted to send and receive calls from potentially hazardous situations such as while driving automobiles, and this increases the hazard of that situation. Furthermore it is becoming more and more unacceptable to be disturbed in public places such as restaurants, by the ringing of mobile phones.